Wall Street is going gaga over Google, prompting some to think the frenzy over the expected — but unscheduled — initial public offering is reaching unhealthy levels that could set up many investors for disappointment. Rumors, misinformation and hopes for fast riches are swirling about the online search engine, creating an eerie flashback to the Internet IPO bubble in the late 1990s.

Any more fervor could threaten the broad IPO recovery by burning investors who end up overpaying. "In the 13 years we've been researching IPOs, we've never seen a more hyped IPO," says Kathy Smith at Renaissance Capital.

Google, which didn't return calls for comment, is not responsible for the mounting hype, because it is saying nothing. The media are clamoring to fill the silence. Some reports have Google filing IPO papers this week; others say it's in no hurry. (Related item: Matt Krantz on recent IPOs)

Sources: Jay Ritter, professor of finance, the University of Florida; USA TODAY research

•It could result in a huge opening move. If an IPO has an opening surge, most average investors can get in only after the initial run-up and expose themselves to big risk.

Of the 10 IPOs with the biggest first-day pops since 1975, not one ever returned to the price it reached its first day, according to an analysis of data from Jay Ritter, professor of finance at the University of Florida.

•It could encourage companies to go public too soon. Being private protects young companies from bending to the often-demanding wishes of Wall Street. It also means growing companies don't have to publicly report financial information that could aid competitors.

Even Google might be going public faster than it wishes. The Securities and Exchange Commission requires private companies to file their financials when they have at least 500 shareholders. Many suspect Google has that many now, because employees have probably received shares.

Peter Thiel, the CEO who took PayPal public and then sold it to eBay (EBAY), says this rule is forcing Google to go public two years too early. He says companies that file financials publicly almost always follow with an IPO.

The last boom had scores of premature IPOs that ended up failing. One example: search engine Excite At Home. While nobody is saying Google is a weak company, there's fear that speculation could take over. "People are looking for the fast buck again — and this might be the one they try to do it with," says professor Irv DeGraw at Washington College.